# filename:

def getNum():   # 获取用户不定长度的额输入
    nums = []
    while True:
        iNumStr = input("请输入数字：")
        if iNumStr != '':
            nums.append(eval(iNumStr))
        else:
            break
    return nums


def mean(numbers):     # 计算平均值
    s = 0.0
    for num in numbers:
        s = s + num
    return s/len(numbers)


def dev(numbers, mean):  # 计算方差
    sdev = 0.0
    for num in numbers:
        sdev = sdev + (num - mean) ** 2
    return pow(sdev / (len(numbers)-1), 0.5)


def median(numbers):  # 计算中位数
    sorted(numbers)
    size = len(numbers)
    if size % 2 == 0:
        med = (numbers[size//2-1] + numbers[size//2])/2
    else:
        med = numbers[size//2]
    return med


n = getNum()
m = mean(n)
print('平均值：{},方差:{:.2}，中位数{}.'.format(m, dev(n, m), median(n)))
